First commit

.github/workflows/build.yml

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+name: build
+on: [push, pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ankane/setup-postgres@v1
+        with:
+          database: pgvector_fortran_test
+          dev-files: true
+      - run: |
+          cd /tmp
+          git clone --branch v0.8.0 https://github.com/pgvector/pgvector.git
+          cd pgvector
+          make
+          sudo make install
+      - uses: fortran-lang/setup-fpm@v5
+        with:
+          fpm-version: 0.10.1
+      - run: fpm run

.gitignore

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+build

LICENSE.txt

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+The MIT License (MIT)
+
+Copyright (c) 2024 Andrew Kane
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# pgvector-fortran
+
+[pgvector](https://github.com/pgvector/pgvector) support for Fortran
+
+Supports [Libpq-Fortran](https://github.com/ShinobuAmasaki/libpq-fortran)
+
+[![Build Status](https://github.com/pgvector/pgvector-fortran/actions/workflows/build.yml/badge.svg)](https://github.com/pgvector/pgvector-fortran/actions)
+
+## Getting Started
+
+Follow the instructions for your database library:
+
+- [Libpq-Fortran](#libpq-fortran)
+
+## Libpq-Fortran
+
+Enable the extension
+
+```fortran
+type(c_ptr) :: res
+
+res = PQexec(conn, "CREATE EXTENSION IF NOT EXISTS vector")
+```
+
+Create a table
+
+```fortran
+res = PQexec(conn, "CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(3))")
+```
+
+Insert vectors
+
+```fortran
+character(256) :: values(2)
+
+values(1) = "[1,2,3]"
+values(2) = "[4,5,6]"
+res = PQexecParams(conn, "INSERT INTO items (embedding) VALUES ($1), ($2)", 2, [0, 0], values)
+```
+
+Get the nearest neighbors
+
+```fortran
+character(256) :: values(1)
+
+values(1) = "[3,1,2]"
+res = PQexecParams(conn, "SELECT * FROM items ORDER BY embedding <-> $1 LIMIT 5", 1, [0], values)
+```
+
+Add an approximate index
+
+```fortran
+res = PQexec(conn, "CREATE INDEX ON items USING hnsw (embedding vector_l2_ops)")
+! or
+res = PQexec(conn, "CREATE INDEX ON items USING ivfflat (embedding vector_l2_ops) WITH (lists = 100)")
+```
+
+Use `vector_ip_ops` for inner product and `vector_cosine_ops` for cosine distance
+
+See a [full example](app/main.f90)
+
+## Contributing
+
+Everyone is encouraged to help improve this project. Here are a few ways you can help:
+
+- [Report bugs](https://github.com/pgvector/pgvector-fortran/issues)
+- Fix bugs and [submit pull requests](https://github.com/pgvector/pgvector-fortran/pulls)
+- Write, clarify, or fix documentation
+- Suggest or add new features
+
+To get started with development:
+
+```sh
+git clone https://github.com/pgvector/pgvector-fortran.git
+cd pgvector-fortran
+createdb pgvector_fortran_test
+fpm run
+```
+
+Specify the path to libpq if needed:
+
+```sh
+FPM_CFLAGS="-I/opt/homebrew/opt/libpq/include" FPM_LDFLAGS="-L/opt/homebrew/opt/libpq/lib" fpm run
+```

app/main.f90

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+program main
+  use iso_c_binding
+  use libpq
+  implicit none
+
+  type(c_ptr) :: conn
+  type(c_ptr) :: res
+  character(256) :: values(3)
+  integer :: ntuples
+  integer :: i
+
+  conn = PQconnectdb("postgres://localhost/pgvector_fortran_test")
+  if (PQstatus(conn) /= CONNECTION_OK) then
+    stop 1
+  endif
+
+  res = PQexec(conn, "CREATE EXTENSION IF NOT EXISTS vector")
+  if (PQresultStatus(res) /= PGRES_COMMAND_OK) then
+    stop 1
+  endif
+  call PQclear(res)
+
+  res = PQexec(conn, "DROP TABLE IF EXISTS items")
+  if (PQresultStatus(res) /= PGRES_COMMAND_OK) then
+    stop 1
+  endif
+  call PQclear(res)
+
+  res = PQexec(conn, "CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(3))")
+  if (PQresultStatus(res) /= PGRES_COMMAND_OK) then
+    stop 1
+  endif
+  call PQclear(res)
+
+  values(1) = "[1,1,1]"
+  values(2) = "[2,2,2]"
+  values(3) = "[1,1,2]"
+  res = PQexecParams(conn, "INSERT INTO items (embedding) VALUES ($1), ($2), ($3)", 3, [0, 0, 0], values)
+  if (PQresultStatus(res) /= PGRES_COMMAND_OK) then
+    stop 1
+  endif
+  call PQclear(res)
+
+  values(1) = "[1,1,1]"
+  res = PQexecParams(conn, "SELECT * FROM items ORDER BY embedding <-> $1 LIMIT 5", 1, [0], values)
+  if (PQresultStatus(res) /= PGRES_TUPLES_OK) then
+    stop 1
+  endif
+  ntuples = PQntuples(res)
+  do i = 0, ntuples - 1
+    print *, PQgetvalue(res, i, 0), ": ", PQgetvalue(res, i, 1)
+  end do
+  call PQclear(res)
+
+  res = PQexec(conn, "CREATE INDEX ON items USING hnsw (embedding vector_l2_ops)")
+  if (PQresultStatus(res) /= PGRES_COMMAND_OK) then
+    stop 1
+  endif
+  call PQclear(res)
+
+  call PQfinish(conn)
+end program main

fpm.toml

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+name = "pgvector"
+
+[build]
+link = ["pq"]
+
+[dependencies]
+libpq-fortran = { git = "https://github.com/ankane/libpq-fortran", branch = "fixes" }
+
+[install]
+library = false